Lesson 7: Genetics

Question 1

Genetics

Answer 1

the specific study of heredity

Question 2

Heredity

Answer 2

the transfer of genetic traits from parent to offspring

Question 3

Gregor Mendel

Answer 3

father of genetics; discovered both parents contribute and equal amount of genes to their offspring, not a blend;

Question 4

What species did Mendel work with and why?

Answer 4

Garden peas:
● reproduce quickly with lots of offspring
● simple traits (tall/short)
● hermaphrodite (can self/crossbreed

Question 5

True-Breeding

Answer 5

only produce the same offspring

Question 6

Mendel’s Theory

Answer 6

for every trait, an individual has two versions of a gene (allele) that can be dominant or recessive (dominant overpowers recessive)

Question 7

Homozygous

Answer 7

Same alleles for a trait
➜ Homozygous dominant - 2 dominant alleles
➜ Homozygous recessive - 2 recessive alleles

Question 8

Heterozygous

Answer 8

● Heterozygous - 2 different alleles

Question 9

Genotype

Answer 9

pair of alleles for a trait (genes)
Ex. AA, Aa, aa

Question 10

Phenotype

Answer 10

the physical trait (caused by the genotype)
Ex. blonde hair, blue eyes

Question 11

If you are heterozygous, the dominant allele is expressed in the ___.

Answer 11

phenotype

Question 12

Each trait is represented by a ___.

Answer 12

letter
● Caps - dominant
● Lowercase - Recessive

Question 13

Standard Punnett Square Genotype Ratio

Answer 13

Homo-d : Hetero : Homo-r

Question 14

Standard Punnett Square Phenotype Ratio

Answer 14

Dom : Rec

Question 15

Law of Segregation

Answer 15

the members of each pair of alleles separate when gametes form ➜ you only give one of each homologous pair of chromosomes to each gamete

Question 16

Law of Independent Assortment

Answer 16

pairs of alleles separate independently
➜ not true for alleles on the same chromosome

Question 17

Complex traits examples

Answer 17

● Alleles can be partially dominant/recessive
● One gene can have more than 2 alleles
● Many genes can impact one trait

Question 18

Complex Patterns of Heredity

Answer 18

● Incomplete Dominance
● Codominance
● Multiple alleles
● X-Linked (Sex-Links) Traits
● Polygenic

Question 19

Incomplete Dominance

Answer 19

heterozygote is a mix of the parents phenotype (neither is dominant), similar outcome to blending theory

Question 20

Incomplete Dominance Ratios

Answer 20

● Genotype - Homo : Hetero : Homo
● Phenotype - Homo : Hetero : Homo
Genotype and Phenotype ratio will be the same

Question 21

Codominance

Answer 21

Both alleles are expressed in the phenotype

Question 22

Codominance ratios

Answer 22

● Genotype - Homo : Hetero : Homo
● Phenotype - Homo : Hetero : Homo
Genotype and Phenotype ratio will be the same
(Same as incomplete dominance)

Question 23

Difference between Incomplete Dominance and Codominance

Answer 23

● Incomplete Dominance:
➜ Red + White = Pink
● Codominance:
➜ Red + White = Red & White

Question 24

Multiple alleles

Answer 24

● More than two alleles possible for a trait
● Blood types determined by 3 alleles: A, B i
● Genotype ➜ Phenotype
- AA ➜ A
- BB ➜ B
- AB ➜ AB (universal acceptor)
- Ai ➜ A
- Bi ➜ B
- ii ➜ O (universal donor)

Question 25

Blood type ratios

Answer 25

● Genotype - 6 outcomes (AA, BB, AB, Ai, Bi, ii)
● Phenotype - 4 outcomes (A, B, AB O)
*Label ratios

Question 26

Non-standard Types of Inheritance

Answer 26

1. Incomplete Dominance
2. Codominance
3. Multiple Alleles
4. Polygenic - Many genes determine a single trait (can’t solve with a Punnett Square)

Question 27

Environmental factors

Answer 27

Your surroundings can influence your phenotype (and in some cases your genotypes)

Ex. Color of an arctic fox in the summer vs. the winter
Ex. Flowers blooming earlier in the spring due to global warming

Question 28

X-Linked (Sex-Linked) Traits

Answer 28

● Carried on only the X chromosome and are recessive (Non X-Linked traits are called autosomal)
● Males are more likely to get these traits because they have only one X chromosome (one chance for the healthy allele)

Ex. Color blindness (X^B - normal color vision, X^b - colorblind)

Question 29

X-Linked Ratios

Answer 29

● Genotype - 5 outcomes (X^B X^B, X^B X^b, X^b, X^b, X^B Y, X^b Y)
● Phenotype - 4 outcomes (Normal vision female (can be a carrier), colorblind female, normal vision male, colorblind male)
*Label ratios

Question 30

Dihybrid Crosses

Answer 30

● Cross 2 traits at once
● Each parent - 4 allele combinations (FOIL)
● Genotype - 9 outcomes
● Phenotype - 4 outcomes
*Don’t need to label but put in order from most dominant to most recessive

Question 31

Pedigree

Answer 31

A diagram showing the lineage of a group used to analyze Inheritance

Question 32

Genetic Disorders vs. Chromosomal Disorders

Answer 32

● Genetic Disorders:
➜ Can be due to mutations in a single gene or multiple genes
➜ Can involve genetic and environmental factors
● Chromosomal Disorders:
➜ Changes in structure or number of whole chromosomes

Question 33

Why are dominant disorders extremely rare?

Answer 33

● An individual who carries even one of the alleles will have the disorder
● If it affects the person before they reproduce, the person will usually die and not reproduce so the mutation would not be passed on
● Many dominant disorders occur later, allowing the person to reproduce

Question 34

Why are recessive disorders found in certain ethnic groups?

Answer 34

People in an ethnic group share certain versions of their genes which were passed down from common ancestors.

Question 35

Multi-Factorial Disorder

Answer 35

a condition caused by multiple factors